Back in high school, this was in the days when computers were new -- only paper readouts, no crt's, programs were stored on ticker-tape strips, etc., and the high schools in the county all networked off a tape drive server at the science center.
My buddies and I wrote a program to steal the dial-up passwords from the other schools in the county. We went around and loaded it into each school's computer when no one was around. Ours was located, literally, in a janitor's closet outside the library...heh.
Once we collected everyone's passwords, we had more time and server space to work on our own programs, got to see what others were working on and discovering, it was pretty cool...and harmless fun...high school kids getting their James Bond on